Heat your oven to 400 degrees F. Rinse your butternut squash and pat it dry.
Heat your squash in the microwave on high for 3-4 minutes to soften it. On a large cutting board, use a large serrated knife to slice off the stem and root ends of the squash. (If you're having trouble cutting through the squash, heat it a little more in the microwave.)
Discard the ends and cut the squash in half the short way. Use a vegetable peeler to remove the skin from the squash halves, peeling until you see orange flesh. (The pale yellow flesh you see first is tough and needs to be removed.) Discard your peels.
Slice each piece of butternut squash in half the long way. (See photos.)
Use a small scoop (if you have one) or a spoon to scrape out the seeds and pulp. Discard the seeds and pulp.
To cut your squash into cubes, first cut the squash into long strips about 1 ½ inches wide. Cut those logs into cubes as shown in the photos.
Place your butternut squash cubes in a single layer on a rimmed baking sheet. Top them as evenly as you can with the olive oil and seasoning. Use your clean hands (or a large spoon) to toss and mix the vegetables. Wash your hands, if needed, and bake the butternut squash for 30 minutes, stopping at the halfway point to flip the squash over with a metal spatula. The squash should be soft, with some crisp edges. You can taste it to see if you want to bake it a little longer.
If your squash weighs less than 2 ½ pounds, you should use less Seasonello. If you don't have a kitchen scale, you can weigh the butternut squash at the store. If you don't have Seasonello, you can use salt and pepper to taste.